A document leaked by Congress shows the Trump administration in late 2017 specifically considered the option of separating families as a way to curb illegal immigration at the border.

The memo, first reported by NBC News and confirmed by ABC News, challenges the assertion by Homeland Security Secretary Kirstjen Nielsen last June on Twitter and in media briefings saying “we do not have a policy of separating families at the border. Period.”

The Dec. 16, 2017, document, provided by Oregon Democratic Sen. Jeff Merkley’s office, which said it received it from a whistleblower, appears to be an internal memo on legal options to address families who were arriving at the border. Among the options listed is the “prosecution of family units” and “separate family units.”

Four months later, in April 2018, the Trump administration announced a “zero-tolerance” policy at the border that resulted in the separation of some 2,700 kids from their families in a matter of weeks.

“Announce that DHS is considering separating family units, placing the adults in adult detention, and placing the minors under the age 18 in the custody of (Health and Human Services) as unaccompanied alien children,” states one option in the document.

AP

In this Jan. 9, 2019, file photo, a man throws a ball for his dog next to the border wall topped with razor wire in Tijuana, Mexico.

Nielsen and other administration officials defended “zero tolerance” at the time and said it was never U.S. policy to separate children.

On Thursday, a spokeswoman for DHS said the document was intended to examine the administration’s options.

“The Trump administration has made clear that all legal options are on the table to enforce the rule of law, rein in mass unchecked illegal immigration, and defend our borders,” said spokeswoman Katie Waldman in an emailed statement.

Waldman said the administration saw an uptick of border arrests, which it blamed on a lack of a border wall and a court settlement that prohibits detention of children for longer than 20 days. Officials have said previously they believe that court settlement, known as the Flores Agreement, encouraged people to travel with minors.

“In part we were predicting — and trying to prevent — the exact humanitarian and security crisis we are confronted by now,” Waldman said. “It would be malpractice to not seriously examine every single avenue to gain operational control of the border and ensure that those who are entering our country have a legal right to be here.”

AP

In this Jan. 11, 2019 photo, a boy plays as floodlights from the United States filter through the border wall in Tijuana, Mexico.

Merkley said in a statement that the documents show the Trump administration was “plotting to create a humanitarian crisis at the border — criminalizing the search for asylum, tearing children from their parents’ arms, and expanding the lock-up of both parents and children.”

In court filings, the administration has estimated a total of 2,737 children were separated from their families under “zero tolerance.” But a report released Thursday by internal government investigators found that there were likely “thousands” more kids separated from families in 2017, before that policy took effect. The Health and Human Services inspector general said that the number of kids separated from their families under the current administration is “unknown.”